1. Field of Invention
Various exemplary embodiments of the present invention relate generally to an electronic device, and more particularly, to a semiconductor memory device and a reading method thereof.
2. Description of Related Art
Semiconductor memory devices are memory devices implemented by using semiconductors such as silicon (Si), germanium (Ge), gallium arsenide (GaAs), indium phosphide (InP), etc. Semiconductor memory devices may be divided into volatile memory devices and nonvolatile memory devices.
Volatile memory devices lose their data when their power supply is removed and examples include a static random access memory (SRAM), a dynamic random access memory (DRAM), a synchronous dynamic random access memory (SDRAM), etc. Nonvolatile memory devices retain their data when their power supply is removed. Nonvolatile memory devices include a read only memory (ROM), a programmable ROM (PROM), an erasable PROM (EPROM), electrically EPROM (EEPROM), a phase-change RAM (PRAM), a magnetoresistive RAM (MRAM), a resistive RAM (RRAM), ferroelectric RAM (FRAM), a flash memory, etc.
When the semiconductor memory device performs a read operation, data of memory cells coupled to a selected word line may be determined as current flows to a common source line through bit lines. That is, depending on whether the current of the bit line is released to the common source line or not, the data of the corresponding memory cell may be determined. When the read operation is performed, however, a large current may flow to the common source line, which may unintentionally increase the voltage of the common source line and reduce reliability of the read operation.